Problem: Jessica ate 1 slice of cake. Michael ate 1 slice. If there were 1 slice remaining, what fraction of the cake was eaten?
Explanation: $\text{fraction of cake eaten} = \dfrac{\text{number of slices eaten}}{\text{number of slices total}}$ Since they ate 2 slices of cake with 1 slice remaining, they must have begun with 3 slices. They ate ${2}$ out of $3$ slices. They ate $\dfrac{2}{3}$ of the cake.